1. Field of the Invention
This invention relates to the loading and upgrading of operating systems on computer systems connected in a network environment.
2. Art Background
An operating system consists of program modules within a computer system that govern the control of equipment resources such as processors, main storage, secondary storage and I/O devices. These modules resolve conflicts, attempt to optimize performance and simplify the effective use of the computer. They act as an interface between the user programs and the physical computer hardware. In order to load an operating system, an I/O device such as a tape drive executes a program resident in the tape drive and inputs the new operating system data into a predetermined area of memory in the computer. During the course of loading an operating system the disk space where the operating system is loaded is erased and re-written with the new operating system data. The amount of information to be loaded on the system is significant and takes one and one-half to two hours to read and down load the information from the tapes.
Before the advent of the distributed systems of today, a single computer system would service a multiplicity of users. Thus when it came time to upgrade the operating system, the system manager would only have to load the new operating system onto a single computer system. However, in today's distributed processing environment, it is quite common that each user has his own computer with its own operating system whereby the computer is networked together with other computers. Thus, when an operating system upgrade is performed, the process of loading the operating system from an I/O device has to be performed with respect to each individual computer system in the network. The upgrade of multiple computer systems can be quite time consuming, and it can be even more burdensome in an operating system development environment where operating system upgrades may be performed as frequently as once a week. Thus, it would be preferable in a distributed environment to load the operating system onto one machine from a tape and thereafter transmit copies of the operating system over the network to each computer system connected to the network.
If the operating system is transferred from one system to another through a network, the amount of time required to load the operating system is decreased. However, to load the system onto a computer in a network environment, the computer system must be booted and running an operating system accessible by the computer hardware and capable of network communication. It should be remembered that when the new operating system is loaded onto the computer the disk space is re-written thereby over-writing and corrupting the existing operating system concurrently being used by the computer hardware. A way to avoid the problem of over-writing the presently used operating system is to boot the computer system to be loaded or upgraded from an operating system resident on another computer in the network. That is, when the computer hardware is powered on a signal is sent out over the network to which the computer hardware with the operating system to be accessed responds. The remote network computer then provides disk partitions on its own local disk for the computer to use. The computer system to be upgraded is then booted using the operating system located on the network computer. Once the computer is booted and active on the network, the new version of the operating system can be down-loaded from the network computer system.
However, in order to utilize such an approach, the network must be configured and initialized to know that when the particular computer is powered on, that computer is to be booted using the operating system accessible on a specific network computer. Thus if the network configuration changes or if it is desirable to boot up from a different network computer than the one initially specified, the network parameters then have to be changed.